So, upon further reading, I was less informed on that than I had thought. The best explanation I could find is here[1]. Basically, ANC does reduce sound pressur

So, upon further reading, I was less informed on that than I had thought. The best explanation I could find is here[1]. Basically, ANC does reduce sound pressure level when it lines up correctly. If you're listening to the sort of ambient noise that it does well with, it gets the phase offset close enough to right to significantly reduce the mechanical force applied to your ear drums. If, on the other hand, you're in an environment where it does a mediocre job, it will still be producing a cancellation waveform, but it won't actually cancel anything, and that will increase the mechanical force applied to your ear drums. So, in an office environment, you'd expect a reduction from the ambient noise of the HVAC system, but an increase from the random nature of your coworkers' conversations. It's hard to say whether you'd have a net reduction or not, but it's not certain, whereas passive noise isolation is certain. [1] http://www.reddit.com/r/askscience/comments/1ios4u/does_producing_antinoise_double_the_amount_of/cb6li32 http://www.reddit.com/r/askscience/comments/1ios4u/does_prod...